Force measuring transducers such as load cells, are well known in the arts. Many different sensing technologies have been used in load cell transducers, such as strain gauge sensing, capacitive sensing, force balance sensing, and variable reluctance sensing. These sensing technologies are well known in the arts. An example of a strain sensor used in load cell manufacturing is described in U.S. Pat. No. 4,064,744, “Strain Sensor extensiometer” to Kistler, while a capacitive sensor is described in U.S. Pat. No. 4,237,989, “Capacitive Load Cell And Method Of Manufacture” to Lewis.
In a related area, acceleration transducers have been described comprising a probe placed in resonant microwave cavity (see, e.g., U.S. Pat. No. 5,546,806, “Microwave Vector Displacement and Acceleration Transducer” to Kain and U.S. Pat. No. 5,261,278, “Microwave Acceleration Transducer” to Kain, each of which is hereby incorporated by reference). An acceleration of the cavity displaces the probe, which causes a variation in the radio frequency (RF) resonant modes of the cavity. The mode changes are then correlated with acceleration values. In comparison to conventional sensors employed for load cell technology, these accelerometer transducers provide the advantage of having an electric signal-generating component that is physically decoupled from the mechanical component of the device.
It would be advantageous if the electric signal-generating components of other displacement-based devices could be physically decoupled from the mechanical components undergoing displacement.